The goal of this exploratory project is to develop and refine a novel battery of processing-based measurement tools that can be used to effectively identify a behavioral phenotype for primary or "specific" language impairment (LI) across children with diverse language learning experiences. Participants will be English-only speakers with and without LI, bilingual speakers of Spanish and English, and bilingual speakers of Hmong and English. We propose 2 types of tasks that emphasize either language processing or the processing of nonlinguistic information. The 3 language-based processing tasks are non-word repetition, counting span and rapid naming, in English, Spanish and Hmong. The 3 non-linguistic processing tasks are choice visual detection, auditory serial memory, and Tallal repetition. Group comparisons followed by likelihood ratios will be used to calculate task sensitivity and specificity. Logistic regression and cluster analyses will be used to determine the best combination of tasks for identifying children with LI and potential LI subgroups. The innovation of this research application is 2-fold: to take the fundamental step of addressing the LI phenotype within the context of linguistic diversity and to develop assessment measures that tap into robust aspects of the information processing system, that is, to examine the nonlinguistic cognitive profile accompanying LI language performance as well as the more observable deficit in language processing. Results from the proposed project will directly contribute to a more clearly defined LI phenotype as well as to the development of non-biased assessment measures needed for separating typical language development from LI in an increasingly diverse population. [unreadable] [unreadable]